1. Field of the Invention
The present invention relates to a heat exchanger having an interior instrument and an exterior instrument, methods for reuse of refrigerant and methods for recovery of the refrigerant used in the heat exchanger, the heat exchange being applicable to various air conditioners used in structures such as building, trains, cars, ships, and airplanes, as well as freezers and refrigerators (including use for vehicles such as ships ) for foods such as fish, vegetables and meats.
2. Description of the Related Art
An air conditioner utilizing heat exchangers generally consists of a separate interior instrument and an exterior instrument. When the separate type air conditioner is used for building structures, the interior instrument is placed inside the house and the exterior instrument is located outside the house. First refrigerant piping which is provided with an interior heat exchanger is joined with the interior instrument and second refrigerant piping which is provided with an exterior heat exchanger is joined with the exterior instrument. The first refrigerant piping and the second refrigerant piping are joined to each other by means of two connecting pipes forming a refrigerant circulating channel along which the refrigerant circulates in the whole air conditioner.
The second refrigerant piping is separately provided with two on-off valves on upper reaches and lower reaches of the refrigerant flow through the exterior heat exchanger. When a leased or rented air conditioner is transferred from an original point of use to a new location on expiration of the contract, or a superannuated air conditioner is carried to a disposal, without release of refrigerant such as chlorofluorocarbons into the atmosphere, the following steps are usually carried out. The air conditioner being set to cooling mode, among the two on-off valves one on-off valve (on-off valve for higher pressure) is closed and the other on-off valve (on-off valve for lower pressure) is opened, and a compressor motor which is arranged between the two on-off valves in the second refrigerant piping is started. Through the steps described above, the refrigerant in the first refrigerant piping and the refrigerant in the connecting pipes are sucked into the second refrigerant piping, and all the refrigerant is sealed in the second refrigerant piping by closing the opened on-off valve. Then the motor is stopped. (these steps are called a pump down).
Pump down cannot occur when the power supply to a building in which the air conditioner is installed is suspended, because the pump down can only be conducted when the compressor motor is on. Thus the electricity supply is a necessary condition for the pump down. And as the pump down is carried out in cooling mode in a reversible air conditioner, it needs a higher environmental temperature than is usual for such an air conditioner which is designed not to be pumped down at below a certain environmental temperature to avoid compressor motor overload.
The purpose of the present invention is to seal in refrigerant used in a heat exchanger such as an air conditioner in as much quantity as possible even when electricity supply is suspended, or even when the outside temperature is below a certain temperature, and to reuse the sealed-in refrigerant at a new place when the heat exchanger is transferred from an original place to the new place, and further to recover the sealed-in refrigerant when the heat exchanger is disposed of.